1. Field of the Invention
This invention relates to a system for dispensing an additive into a flowing stream of fluid at a rate proportionate to the rate of increase in the flow of the fluid, and more specifically, to a stationary vehicle refueling system for dispensing additive into a fuel flow at a rate proportionate to the rate of the fuel flow, particularly when the refueling cycle is brief.
2. Description of the Related Art
Fuel additives, when mixed in proper proportion, provide greater engine efficiency by improving fuel combustion, inhibit fuel from freezing in sub-zero conditions, clean fuel injectors, and reduce over-all engine wear. The additive can also serve to control the emission of unburned hydrocarbons resulting from the combustion cycle, such as in a diesel engine. In the past, fuel additives were manually dispensed into fuel tanks in measured amounts. However, this method did not always result in mixing the fuel and additive in proper proportion.
More recently, fuel additive systems have been introduced which dispense fuel additives in proportion to the amount of fuel pumped into a particular tank. One example of such a system is described in U.S. Pat. No. 4,253,436 to Dudrey. This system includes a control unit for delivering a predetermined quantity ratio of additive based on the calculated quantity of fuel loaded into the fuel tank. More particularly, the control unit functions to operate the system for a proportional time period to inject the proper quantity of additive.
Another fuel additive system is described in U.S. Pat. No. 4,621,593 to Rao et al. This system includes an apparatus for dispensing an additive into a fuel tank in dependence upon the level of fuel within the tank. U.S. Pat. No. 5,195,466 to Schulte et al. describes a method for controlling the addition of an additive into the fuel supply of a vehicle engine while the vehicle is in motion and the engine is in operation. This method involves measuring the fuel level in the vehicle fuel tank at predetermined time intervals and comparing those measurements to previously measured fuel levels. Additive is then dispensed into the fuel tank in proportion to the variations in the fuel level.
Other on-board fuel additive systems are disclosed, for example, in U.S. Pat. Nos. 4,161,160 to Hicks et al.; 4,329,945 to Beech et al.; 4,568,248 to Harders; and 4,727,827 to Hoffman et at. In general, these systems are not readily adaptable for use in conjunction with a stationary depot refueling facility, and do not include suitable structures and/or controls for ensuring that the fuel and additive will be mixed thoroughly and in proper proportion.
Accordingly, there is a need in the art for a method of and apparatus for dispensing an additive into fuel by injecting a proportioned amount of the additive into the fuel flow from a stationary storage reservoir as the fuel is loaded into a vehicle fuel tank. There is also a need in the art for novel flow rate control structure to accurately control the rate of increase in the flow rate of the liquid initially flowing through the system during the entire refueling cycle so as to accurately control the amount of additive introduced into the flowing liquid, as well as structures for efficiently mixing the fuel and additive as both pass through the system.